Shaft furnace for indurating pellets



Aug. 19, 1958 H. WYNNE ETAL 2,848,208

SHAFT FURNACE FOR INDURATING PELLETS Filed June 21. 1951 5 Sheets-Sheet 1 BY A eW/ve-WM Mae? W m ,4;- Nays 1; .WYNNE EIAL 2,848,208

SHAFT FURNACE FOR INDURATING PELLETS Aug. 19, 1958 5 Sheets-Sheet 2 Filed June 21, 1951 Aug. 19, 1958 1. H. WYNNE ETAL 2,848,208

SHAFT FURNACE FOR INDURATING PELLETS Filed June 21. 1951 5 Sheets-Sheet :5

IN VEN TORS BY Mew/very! Mae-Y Arr Ys United States Patent 2,848,208 I SHAFT FURNACE FOR INDURATLNG PELLETS Ira H. Wynne, Milwaukee, and Henry K. Martin, Montreal, Wis., and Kenneth M. Haley, Ashland, Ky., assignors to Oglebay, Norton and Company, Cleveland, Ohio, a corporation of Delaware Application June 21, 1951, Serial No. 232,686

22 Claims. (Cl. 263-49) This invention relates to shaft furnaces and, more particularly, to a novel mechanism controlling passage of material through such a furnace which, while not limited thereto, is especially useful for heating pellets formed from fine particles of metalliferous material.

It is often necessary to crush metalliferous materials to fine particle sizes in order to remove the gangue therefrom. However, since it is usually desirable to have the metalliferous material in relatively large pieces for smelting and other metallurgical processes, the relatively fine size particles of the material must be agglomerated. Likewise, flue dust and other fine particles of metalliferous materials cannot be readily utilized in smelting or the like without agglomeration.

One mode of agglomerating the above-mentioned and other metalliferous materials, when in fine particle sizes, into bodies of suitable size for metallurgical processes is by compacting the particles into substantially symmetrical pellets. This may be effected by a procedure such as disclosed by Firth in Patent No. 2,411,873 or by other known procedures which produce substantially ball-like bodies. For the purpose of simplicity, fine particles of metalliferous material which have been agglomerated into larger bodies by balling or other known procedures will be hereinafter referred to as pellets, it being understood that this term is used in a generic sense, and is not intended to be limited to substantially spherical agglomerates formed from iron ore concentrates by the procedure disclosed by Firth but is intended to include all agglomerates formed from fine particles of metalliferous material.

Pellets as formed by the Firth and other known procedures are generally somewhat moist and upon drying are relatively fragile but may be sufficiently hardened by heating to permit handling thereof by conventional ore-handling equipment. This heating of the pellets should be substantially uniform to eifect the desired degree of hardening in all the pellets but must not be such as to cause fusion resulting in the formation of unduly large clusters of the pellets. Moreover, since the pellets are relatively fragile before they have been heated, they must not be subjected to forces resulting in substantial breakage or brasion during the early part of the heating.

The principal object of this invention is, therefore, the provision of an improved shaft furnace which is so constructed and arranged that it will satisfactorily effect heating of pellets, formed from fine particles of metalliferous material or the like, which are substantially continuously charged into the top and removed from the bottom of the furnace whereby the heating is effected as a continuous operation without undue breaking of the unheated pellets and any excessively large clusters of the heated pellets may be readily broken prior to discharge.

Another object of the invention is to provide a shaft furnace for hardening pellets, for-med of fine metalliferous material or the like, with improved mechanism for controlling the passage of material therethrough, the said mechanism being so constructed and arranged that the pellets in any horizontal plane move downwardly through 2,848,208 Patented Aug. 19, 1958 ice the furnace, at a controlled rate, preferably substantially uniformly, and the heated pellets may be subjected to suflicient agitation or breaking action adjacent the bottom of the furnace to break up any large clusters of pellets which may form, thereby facilitating discharge.

A further object of the invention is the provision of a shaft furnace with discharge control mechanism of the type mentioned in the preceding object and wherein individually supported, elongated, breaker rolls extending transversely of the furnace are provided to effect the said crushing or breaking of excessively large clusters of pellets through a rocking action imparted to the rolls.

A still further object of the invention is the provision of a shaft furnace of the type mentioned and wherein the.

rate of movement of the material through the furnace is controlled by a plurality of spaced gate members horizontally disposed and extending transversely of the furnace below the openings between the above-mentioned breaker rolls, the said members being adjustable to vary the discharge openings therebetween through which the material in the furnace passes and comes to rest upon horizontally disposed members therebeneath, means being provided to effect displacement of material from the last: mentioned members in a manner such that the individual pellets of the material in any horizontal plane within the furnace may move downwardly at :a predetermined rate.

A more specific object of the invention is the provision in a shaft furnace, for hardening pellets of iron ore concentrates or the like by heating, of a plurality of spaced breaker rolls extending transversely of the shaft of the furnace adjacent the bottom thereof and supported for limited rocking movement, a plurality of adjustable arcu ate gate members extending transversely of the furnace below the breaker rolls also being provided for controlling the passage of material onto substantially horizontally disposed members beneath the openings between the said gate members, the said horizontally disposed members including portions reciprocable for discharging a part of the pellets resting thereon and the said arcuate gate members including flexible means depending therefrom to assist in defining the angle of repose of the pelletized material on the horizontal members.

An additional object of the invention is the provision of a shaft furnace for hardening pellets of iron ore concentrates or the like by heating, which furnace has material discharge controlling mechanism of the type mentioned and further provided with means to introduce gas adjacent said mechanism to assist in heating the pellets, which gas may be air, oxygen, or mixtures thereof with heat producing gaseous substances, means being provided to regulate the composition and/ or volume of the gas thus introduced into the furnace.

The invention further res-ides in certain novel features of construction and combination and arrangements of parts, and further objects and advantages thereof will be apparent to those skilled in the art to which the invention pertains from the following description of the present preferred embodiment thereof described with reference to the accompanying drawings in which similar reference characters represent corresponding parts in the several views and in which,

Fig. l is a fragmentary vertical sectional view through the lower portion of a shaft furnace constructed in accordance with this invention, the view being taken substantially on the line 11 of Fig. 2 with certain parts broken away to more clearly reveal the construction;

Fig. 2 is a fragmentary vertical sectional view taken substantially on the line 2-2 of Fig. 1 with certain parts broken away and others omitted and with a quantity of pellets disposed therein;

Fig. 3 is a fragmentary side elevational view of the portion of the furnace shown in Fig. 2, the view being 3 7 taken from the right of Fig. 1 as indicated by the line 3-3;

Fig. 4 is a fragmentary view on an enlarged scale of a portion of Fig. 1 illustrating the tuyeres with the air and/ or gas supply means for the furnace shown in greater detail;

Fig. 5 is an enlarged detached fragmentary elevational view of the driving means for one of the feeder or discharge bars of the furnace;

Fig. 6 is a sectional view taken substantially on the line 6-6 of Fig. 5;

Fig. 7 is a sectional view taken substantially on the line 7-7 of Fig. 5 and showing the means for limiting movement of the feeder or discharge bars;

Fig. 8 is an enlarged fragmentary view, partly in section and partly in elevation, of the end portion of one of the roll-type material breakers or crushers employed in the furnace, the view representing the right-hand portion of one of these members as viewed in Fig. 1;

Fig. 9 is a fragmentary end view of one of the breaker rolls as seen from the right in Fig. 8, the crank arm therefor being shown attached thereto;

Fig. 10 is a fragmentary side elevational view of a portion of the furnace as seen from the right of Figs. 1 and 4 illustrating the means for controlling the valves regulating the flow of air and/or gaseous fuel to the tuyeres and,

Fig. 11 is an enlarged fragmentary side elevational view of a portion of Fig. 1 showing the means for adjusting the positions of the gate members.

It will be appreciated that the furnace embodying this invention may be utilized for operations other than hardening pellets of metalliferous material by heating but because the construction thereof renders it especially useful for this purpose the subsequent description will be restricted to such a use. It is to be understood, however, that this restriction is only for the purposes of clarity and is not be be considered as a limitation of the invention.

Referring now in detail to the drawings, it will be seen that the invention is embodied in a shaft furnace, designated generally 20, which is preferably of rectangular cross section. The furnace comprises a shell 21 formed of steel plates suitably secured together and reinforced by channel members 22, the furnace being supported at the desired elevation by vertically extending standards or legs, such as 23, 24, 25 and 26, likewise formed of channel members. As will be seen from Figs. 1, 2 and 4, the upper portion of the shell 21 is provided with a suitable refractory type lining 27 thereby forming the shaft proper or treatment chamber of the furnace, a portion of the shell 21, in the form of horizontally disposed plates 28, extending inwardly beneath the lining 27 to retain the latter in place. Suitable reinforcements are also provided beneath the lining by channel members such as 29 forming a rectangular frame secured to the tops of the aforementioned legs 23, 24, 25 and 26.

Connected with the plates 28 and the innermost channel members 29 at opposite sides of the furnace are downwardly extending plates 30 and 31 substantially in alignment with the inner surface of the lining 27 and completely covering the channel of the innermost channel members 29. Below the plates 30 and 31 the shell of the furnace continues in the form of downwardly extending plates 32 and 33 which are secured to the legs 23, 2d, 25 and 26 and the channel members 29. The ends of the furnace are likewise provided with downwardly extending plates 34 and 35 which are substantially in alignment with the inner surface of the lining 27 of the furnace and extend to a region lower than the lower edges of plates 30 and 31.

The mechanisms controlling the movement of the material in the furnace through the latter and effecting breaking of the large clusters of the material which may be formed are located in the portion of the shell of the furnace below the lining 27 and substantially enclosed by the previously mentioned plates 32, 33, 34 and 35 comprising the lower portion of the shell of the furnace. These plates merge into two downwardly converging hopper shaped parts 36 and 37 through which the material from the furnace may be discharged for storage or further treatment. The lower portions of these hopper shaped parts 36 and 37 may be provided with suitable discharge controlling valves if desired which, however, are not herein shown since they form no part of the present invention.

The pellets of iron ore or other metalliferous material to be heated in the furnace may have incorporated therein a small quantity of coal, coke, oil, or other fuel and this material may be sufiicient to, at least in part, supply the necessary fuel for heating the pellets, in which event only air or oxygen need be supplied to the furnace once the latter has been placed in operation and the temperature initially raised to a value suificient to cause combustion of the said fuel. However, the furnace of this invention is also capable of operating when the quantity of fuel supplied within the pellets or around the pellets is insufficient to provide all of the necessary heat. For this purpose, the furnace has provisions for supplying fuel in gaseous form as well as air or oxygen.

In order to introduce the gas, which may be air, oxygen, and/or mixtures therewith of gaseous fuels, the furnace is provided, in accordance with this invention, with a plurality of tuyeres preferably spaced along opposite sides of the furnace adjacent the discharge controlling mechanism. As shown in Figs. 1, 4 and 10 of the drawings, two rows of such tuyeres may be provided on each side of the furnace which rows are vertically spaced from each other with one row or set of tuyeres, generally designated 33, adjacent the bottom of the lining of the furnace and the other row or set of tuyeres, generally designated 3?, at a lower elevation adjacent the discharge controlling mechanism. If desired, additional tuyeres could be provided below the discharge controlling mechanism within the hopper shaped portions such as 36 or 37 or at points intermediate the various instrumentalities of the discharge mechanism hereinafter described.

In the illustrated form, the tuyeres 3S and 39 preferably are provided as elongated tubes such as 40 which are adjustably mounted within tubes or housings 41 passing angularly through the side walls of the furnace. Thus, the upper rows of the tuyeres 38 have the tubes 41 thereof embedded in the lining 27 of the furnace while the lower rows or sets of tuyeres 39 have the outer tubes thereof passing through openings in the channel members 29 and the plates 30, 31, the tubes being welded thereto. Preferably the tuyere pipes 40 are adjustable within the mounting pipes 41 so that the tuyeres may be made to project into the interior of the furnace a short distance, if desired.

Referring now to Figs. 4 and 10, it will be seen that the tubes or pipes 40 of the tuyeres are each connected by separate elbow members 42 to separate pipe members 43 which communicate through separate valves 44 with a bustle pipe 45 conducting air or oxygen to the furnace from a suitable source of supply, not shown. The bustle pipe 45 preferably encircles the furnace and is secured to one of the channel members 22 thereof by suitable mounting members 46, see Figs. 1 and 4. Below the bustle pipe 45 is a gas manifold 47 which may likewise be supported by the members 46 from the channel member 22, this manifold encircling the furnace beneath the bustle pipe 45 and being connected with a suitable supply of gaseous fuel.

At spaced points along the length of the manifold 47, corresponding in location and number with the number of tuyeres, are connections to valve members 48 which may each be adjusted to provide the desired volume of flow therethrough by means of a lever 49 and a pull rod 50, the latter extending upwardly to a convenient point adjacent the top of the furnace, see Fig. 10. The pull rods 50 may be provided adjacent the tops thereof with suitable means for effecting raising and lowering thereof and retaining them in an adjusted position, the maximum movement of the rods being indicated by broken lines in Fig. 10. The gaseous fuel passing through each of the valves 48 next passes through metering valves 51 provided in the lower portion of the air valves 44 and which may be adjusted by the knobs or handles 52 thereof. The gaseous fuel then continues through connections 53 each including pipes extending into the interiors of the pipes 43 and provided with nozzles 54 therein so thatthe gaseous fuel may be readily mixed with the air or oxygen flowing through the pipes 43. Adjustment of the valves 44 may be effected by means of the actuaing rods 55 which preferably extend adjacent the top the furnace, see Fig. and are each provided with a pipe T or the like 55a through which an actuating rod may be passed for effecting turning of the corresponding valve and hence adjustment of the flow of air or oxygen.

It will now be apparent that by manipulation of the actuating rods 50 and 55 the flow of gas to the furnace may be readily controlled so as to provide all air or oxygen or mixtures thereof with a gaseous fuel and that the proportion of the mixtures may be readily varied. Furthermore, the quantity and nature of the gas supplied to any given tuyere may be individually adjusted if desired to thereby regulate the heating effect in any given portion of the furnace so that the desired uniformity of heating effects within the furnace may 'be secured.

Extending transversely of the furnace beneath the material treating portion, defined by the lining 27, is the discharge control mechanism including the mechanism for breaking excessively large clusters of the pelletized material which may form in the event some or all of the pellets are excessively heated. As shown more particularly in Figs. 1 and 2, the plates 32 and 33 are provided with spaced aligned apertures for receiving transversely extending breaker rolls, generally designated 56, the axes of which extend in parallel relationship and substantially horizontal.

The spacing of the breaker rolls 56 is such as to provide open passageway between adjacent rolls. This permits the passage of such size material as does not require breaking of clusters, as well as the material resulting from the operation of the rolls upon large clusters of the pelletized material. These breaker rolls are'each preferably formed of an elongated pipe 57 having a slightly reduced diameter portion 58 adjacent the ends thereof extending through gas seals 59 which are secured to closure plates 60 providing covers for the openings in the plates 32 and 33 through which the rolls may be insel'ted into the furnace and removed therefrom. Extending through the pipe 57 of each breaker roll 56 is a shaft 61 which is secured in spaced central relationship with respect to the interior of the pipe 57 of the roll by end plates 62 welded to the pipe and shaft, respectively. The shafts 61 of the breaker rolls extend outwardly of the furnace shell and are each journalled for rocking movement by bearings 63 supported upon suitable frame members 64 which are in turn supported from the legs 23, 24, 25 and 26 by vertically extending support members 65 attached to the said members 64 and the channel members 29 as well as to the legs 23, 24, 25 and 26, see Fig. l.

The breaker rolls 56 are preferably provided with water-cooling means to prevent seizing of the shafts 61 within the bearings due to the heat imparted thereto from the furnace and this cooling of the breaker rolls also performs the further desired function of reducing the temperature of the pellets as they are discharged from the furnace, thus facilitating handling without the necessity of an extended cooling period. This cooling of the rolls is effected by providing a longitudinally extending bore 66 in the outer ends of each of the shafts 61 and extending into the latter beyond the region of the end plates 62, each bore 66 communicating with a transversely extending bore 67 within the pipe 58 thereby providing a passageway through the roll which extends from one bore 66 through its connecting bore 67 to the space between the shaft 61 and the pipe 57 thence through the communicating bores 67, 66 at the other end of the shaft 61. A source of cooling medium such as water or the like may be connected to each of the bores 66 at one end of each of the breaker rolls 56 by connections such as 68 extending from a common manifold 69. The other ends of the rolls have their bores 66 connected with exhaust conduits or pipes 70 leading to a trough 71 which may be supported from the lower tuyeres such as 39, the trough extending along one side of the furnace and emptying through a discharge pipe 72.

In order to effect breakage of any excessively large clusters of the pellets which may form in the furnace and which could not be readily discharged between the rolls 56, the latter are provided with outwardly extending projections in the form of teeth 73 and the rolls are rocked by power means. As shown in the drawings, see particularly Figs. 1, 2 and 8, the teeth 73 may be in the form of separate members having reduced base portions 74 fitted into the recesses in the outer surfaces of the pipes 57 and welded therein, there preferably being two rows of spaced projections or teeth 73 on each pipe or breaker roll.

Oscillation or rocking of the breaker rolls 56 is pref erably effected by fluid pressure mechanism there being one such mechanism for each of the rolls so that the latter may be individually rocked at a desired rate without interfering with movement or lack of movement of the other rolls. In this manner the excessively large clusters between any pair of rolls may be readily broken.

Moreover, in addition to their breaking action the rolls.

effect a feeding of the material within the furnace downwardly therethrough similar in nature to rocking of grate bars in a conventional furnace so that the rate of movement of the material within the furnace may also be controlled by rocking of the breaker rolls whether or not any clusters of pellets are to be broken. Thus, if it be found that the pellets or other material in the furnace are not descending uniformly throughout all parts of the horizontal cross section thereof, the breaker roll or rolls under the slower moving portion of the material may be operated to speed up movement of the material in that portion of the furnace. Likewise, if material be moving downwardly uniformly in the furnace but at a rate which is deemed unnecessarily slow the rate of movement may be speeded by rocking all of the breaker rolls.

In accordance with the illustrated embodiment of the invention, the mechanism for effecting rocking of each of the breaker rolls is individual to that roll and is identically constructed. Consequently, only one need be mentioned in detail. As shown in Figs. 1, 3 and 9, each of the rocking mechanisms comprises a crank arm 75 which has a substantially rectangularly shaped opening at one end fitted upon a correspondingly shaped portion 76 at one end of the shaft 61. The other end of the crank arm 75 is preferably bifurcated and is connected with the piston rod 77 of a piston and cylinder assembly, generally designated 78, mounted upon a supporting member 79 secured to the legs 24 and 26 and the adjacent support members 65. A shield or guard 79a is preferably provided over the joints between the arms 75 and piston rods 77.

Rocking of the crank arm 75, and hence of the corresponding breaker roll 56, is effected by alternate introduction of fluid under pressure into the piston and cylinder mechanism 78 through the conduits or pipes 80, 81 under control of a valve generally designated 82. The valve 82 is of conventional construction and may be either automatically or manually controlled at a location remote from the furnace, in a well known. manner, to cause the piston and cylinder mechanism 78 to act as a fluid motor effecting rocking of. the associated breaker roll 56. Preferably, each valve 82 is controlled by a timer mechanism so that they are repeatedly operated in predetermined sequence, with manual controls provided for individual operation independent of the timing mechanism. Alternatively, one or more of the breaker rolls 56 may be cyclically operated in accordance with the movement of any other member of the furnace, if desired, by suitable conventional controls connected to the valve or valves 82.

Fluid for effecting operation of the breaker rolls rocking mechanisms is supplied to the several valves 82 through individual connections 83 extending from manually controlled valves 84 which are in turn connected with a manifold 85 leading to a suitable source of supply of fluid under pressure, not shown. Fluid for operating the piston and cylinder organizations 78 is preferably air or other gas under pressure since this provides a resilient or compressible medium intermediate the source of power and the breaker rolls 56 so that, if a particularly hard or exceptionally large cluster of pellets should be lodged adjacent the breaker rolls and cannot be broken by the usual force exerted by the rolls in attempting to rock, the mechanism will not be broken when rocking of the rolls is attempted. In the event the fluid employed is substantially incompressible such as oil or the like, or if an electric motor or the like is to drive the breaker rolls, a compressible medium may be interposed between the rolls and the power source by employing a lost motion connection utilizing a compressible spring or the like, as will be apparent to those skilled in the art of mechanical movements.

Above the breaker rolls 56 and substantially intermediate the latter, the side plates 32 and 33 are provided with poke holes normally closed by sealing plugs 86. These poke holes are provided to facilitate breaking and/ or removal of excessively large clusters of material which cannot be readily broken by the breaker rolls in the event any such clusters are formed. In addition, the said poke holes provide a means through which the interior of the furnace may be inspected, thermocouples or the like inserted, and other desired operations performed.

As mentioned heretofore the material within the furnace must pass between the breaker rolls 56 in being discharged from the furnace. The breaker rolls are substantially uniformly spaced from each other and this spacing is preserved adjacent the ends of the furnace by stationary semicylindrical tubes 87 or dummy breaker rolls secured to the end plates 34 and 35. These dummy breaker rolls or stationary tubes, however, have no outward projections or fingers in order that material may not lodge therein since the said tubes are not rocked.

The approximate limits of the rocking movement of the breaker rolls 56 will be readily apparent from an inspection of Figs. 2 and 3. Thus, in Fig. 2 the outermost fingers 73 shown in solid lines represent one limit of their movement while the broken line positions of the fingers illustrate the other limit of movement. The limits of movement are also represented in Fig. 3 wherein one of the crank arms 75 is shown at. one limit of its movement and the other crank arms are at the other limit of movement.

At the ends of the furnace, and secured to the shell thereof at a point below the above-mentioned stationary scmicylindrical tubes 87, are inverted, V-shaped deflector members 88 which are adapted to direct pellets passing between the said stationary tubes 87 and the adjacent breaker rolls 56 to the region beneath the latter. Intermediate the end deflector members 88 and extending transversely of the furnace in spaced parallel relationship are other similar inverted V-shaped deflector members 89, there being a V-shaped member 89 beneath alternate ones of the breaker rolls 56, Consequently, the deflector members 88 and 89 act to direct pellets passing between the breaker rolls on either side thereof to a region substantially directly beneath alternate ones of the breaker rolls, as will be clearly apparent from Fig. 2.

The extent of the opening between the edges of adjacent deflector members 88 and 89 is adjustably controlled by gate members, generally designated 90. These gate members extend transversely of the furnace and are preferably arcuate in cross section and may be either scmicylindrical castings or plates integral with or secured to spaced radially extending arms 91. The arms 91 are connected with shafts 92, journalled in the sides of the furnace, so that rotation of the shafts 92 adjusts the angular positions of the gate members thereby altering the openings therebetween. and to retain the gate members in their adjusted positions, the shafts 92 extend through the plates 32 and in sealing relationship and the one outer end of each of the shafts is provided with an arm 93 connected thereto, see Fig. 11, which arm 93 tends to move downwardly under the weight of the associated gate member 99. Each arm 93 is provided with an enlarged boss 94 forming a bearing point for a cooperating adjusting screw 95 which passes through a nut 96 welded to a flange of the support member 64. The screw 95 is provided with a polygonally-shaped head 97 by which it may be rotated to adjust the position of the corresponding gate member 96, the latter remaining in the adjusted position as aforementioned due to its tendency to rotate in the downward direction. Each screw 95 is also preferably provided with a nut 98 which may be tightened against the lower surface of the flange of the member 64, after the screw has been properly positioned, to prevent displacement of the screw due to vibration or the like.

Material passing between the gate members 90 is adapted to collect upon horizontally extending members, generally designated 99, positioned below the spaces or openings between the gate members 90 and extending transversely of the furnace. These horizontally extending members include both stationary and reciprocating portions or members, the latter being provided for dislodgement of the pellets or other material thereby controlling the movement of material through the furnace. In order to define the angle of repose of the pellets or other material upon the horizontally extending members 99 and thereby further regulate the rate of movement of pellets or other material through the furnace, the lower edge of each of the gate members 90 is provided with flexible means extending downwardly therefrom and which is adapted to contact the pellets or the like as they pile up on the said horizontally extending members 99.

In the illustrated embodiment, the above-mentioned flexible means comprise short lengths of chain 100 connected to the inner side of each gate member 90 at longitudinally spaced points therealong adjacent the lower edge thereof. The lower ends of the chains 100 extend below the gate members and are provided with weighted members or balls 101 tending to hold the chains in a vertical position. The weight of the chains 100, balls 101 and the angular position of the gates 90 coact to define the angle of repose of the pellets or other material upon the horizontal members 99. Thus, with the gates positioned as shown in Fig. 2, the chains 100 and balls 101 would take up positions somewhat as indicated under influence of the pellets P collected upon the members 99. The gate members 90 may be so adjusted that, when neither the breaker rolls 56 nor the above-mentioned horizontally reciprocating portions of the members 99 are actuated, the pellets P will not be discharged from the horizontal members 99. However, by adjusting the gate members 90 to a more elevated position, the angle of the outer surface of the pellets collecting upon the horizontal members 99, which is defined at least in part by the chains 100 and balls 101, will exceed the angle of repose and hence the pellets will tend to flow beneath the chains 100 and balls 101. This flow may be assisted by rock- To effect this adjustment gar ges ing one or more of the breaker rolls 56 as previously described. However, the primary means for effecting feeding or discharge of the material from the members 99 is not gravity flow or rocking of the rolls 56 but rather reciprocation of the movable portions of the members 99 as is about to be described.

The horizontally extending members 99 includes spaced pairs of substantially horizontally extending T-shaped members 102 the ends of which are secured to the side plates 32 and 33 with the vertical web of the members extending downwardly so that their upper surfaces are substantially planar. Resting upon adjacent edges of the two members 102 of each pair of transverse T-shaped members at a T-shaped member 103 with the central web thereof extending upwardly, see Fig. 2. The members 103 are the aforementioned movable members or portions and are slidably supported upon the upper surface of the plates or members 102 for transverse reciprocating movement, the members 103 being guided in this movement and prevented from displacement relative to the plates 102 by spaced plates 104 connected with the members 103 and extending underneath the adjacent members 102 on either side of the opening therebetween, see Fig. 7. The desired spacing between each plate 104 and the member 103 is secured by a filler member 105 the width of which is such as to define the limits of reciprocating movement of the member 103 by abutting the edges of the adjacent members 102.

The members or feeder bars 103 are individually reciprocated by providing segmental racks 106 on the undersides and adjacent the ends thereof which racks cooperate with pinions 107 upon transversely extending shafts 108 there being a separate shaft 108 for each of the members 103. The shafts 108 extend outwardly of the shell of the furnace and are adapted to be given a rocking movement of preselected amount by individual driving mechanisms, generally designated 109. The driving mechanisms 109 each comprise a separate electric motor 110 connected through a speed reduction mechanism 111 to the shaft 112, see Figs. and 6, which shaft has an eccentric portion 113 intermediate its ends. The eccentric portion 113 is provided with a bushing 114 upon which is journalled one end of a connecting rod 115. The rod 115 extends through an opening in the housing 116 for a portion of the mechanism 109 and the other end of the rod is positioned between two apertured disks 117 and 118 with a stud passing through the rod 115 and aligned apertures in the disks providing a connection therebetween. The disks 117 and 118 are mounted upon the shaft 108 and connected to turn therewith. Hence, it will be apparent that when the shaft 112 is rotated by the driving mechanism 109 the eccentric portion 113 will rock the connecting rod 115 and the latter will in turn rock the shaft 108 thereby causing the pinions 107 to rock and this, in turn, reciprocates the members 103 so as to move the pellets upon the plates 102 towards and over the outer edges thereof. Since the members 103 are each provided with individually operated driving means 109, the rate of discharge of the material in different regions transversely of the furnace may be readily controlled by varying the energization of the driving means; that is to say, by allowing certain of the said means to remain stationary and driving others or by driving all at the same or different speeds of operation depending upon the desired rate of movement of material in the furnace. In order to retain the racks 106 in engagement with the pinions 107 and prevent longitudinal displacement of the members 103, the latter are preferably provided on their under surfaces with angularly shaped guiding members 119 having downwardly extending flanges 120 cooperating with rollers 121 on the shafts 108.

It is believed that the operation of the shaft furnace constructed as described will be apparent from the above detailed description of the several parts thereof. How- 10 ever, in order to facilitate understanding, the operation will be briefly summarized.

The furnace is charged by employing a suitable means, not shown, to lay down successive layers of green pellets Within the shaft of the furnace, which pellets are to be heated to the desired temperature, filling being continued until the shaft or treatment chamber of the furnace is substantially completely filled whereupon the rate of filling is thereafter maintained in accordance with the rate of discharge of the pellets so that the shaft or treatment chamber is maintained substantially uniformly full at all times. If the pellets contain a certain amount of fuel therein or thereabout, they may be satisfactorily heated by simply introducing air or oxygen through the tuyeres by means of adjusting the valves 44, the air or oxygen being introduced through the bustle pipe 45. When the fuel in or about the pellets is sufficient for all of the heating, the valves 48 may be entirely closed so that no gaseous fuel-is introduced. Uniform heating through the furnace may be secured by individually adjusting the separate valves 44 through manipulation of the valve actuating rods as previously described. Where, however, the pellets do not contain or have fuel placed thereabout, or the quantity of this fuel is insuflicient to supply all of the heat needed, a gaseous fuel may be introduced into the furnace through the tuyeres in mixture with the air or oxygen through suitable operation of the valves 48, the composition of the mixture being controllable for each individual tuyere through the individual valves 48 thereof which may be manipulated by their rods 50.

Movement of the pellets downwardly within the shaft of the furnace is at a rate to provide sufiicient heating thereof to effect hardening without fusing the pellets into excessively large clusters, although small clusters of pellets are not objectionable. The optimum rate of movement will depend upon a number of variables such as the size of the furnace, composition of the materials forming the pellets treated, size of the pellets, and other considerations which do not form any part of this invention and which can be readily determined by experiment. Suffice it to note that whatever the desired rate of movement of the pellets it can be secured and controlled, as desired, through the mechanisms of this invention so that the pellets are properly heated and discharged from the furnace. Thus, the rate of flow of the pellets downwardly through the furnace is in part controlled by the setting of the gate members to vary the openings therebetween and in part by the number and rate of operation of the reciprocating feeder bars or members 103. In addition, movement of the material through the furnace is facilitated and excessively large clusters of pellets are broken by rocking movement of one or more of the breaker rolls 56.

In brief, if it be found that the pellets in one portion of the furnace are discharging at too slow a rate, the gate members 90 in that region of the furnace will be opened wider and/ or the feeder bars or members 103 reciprocated at a faster rate. or the discharge is not uniform at this point this will no doubt indicate that one or more clusters of pellets have lodged between the breaker rolls and hence these may be operated to break the clusters and resume the flow of material. Conversely, excessively rapid flow of material through the furnace in a given region thereof may be reduced by stopping or slowing down the corresponding feeder bar or member 103 and/ or by adjusting the gate members 90 in that region closer together. Likewise, cessation of rocking of the breaker rolls will slow down feeding through a given region.

It will be evident, therefore, that by this invention the flow of material through the furnace may be controlled with great facility so that a more uniform movement of material is possible than in prior devices. This makes for a more uniform heat treatment of the pellets and hence a more satisfactory product. In other words, the separate If no discharge occurs at a given point pellets in any horizontal layer of the material within the furnace may be made to move downwardly at substantially the same rate so that all the pellets within such a hypothetical layer are subjected to substantially the same temperatures for the same periods of time.

While the invention has been illustrated and described in considerable detail as embodied in a rectangular shaft furnace for hardening pellets of iron ore, it will be readily understood that the furnace is not limited to such a use but may be employed for other purposes where similar problems are encountered. Furthermore, variations may be effected in the details of construction of the device. For example, as mentioned heretofore, the breaker rolls may be either individually operated or cyclically controlled automatically as may be desired through the use of conventional mechanisms for controlling the valves 82. Likewise, the feeder bars or members 103 may be either simultaneously or individually operated and may employ other driving means than those herein shown. Also, the driving means for the breaker rolls may be other than the fluid pressure mechanisms illustrated. Furthermore, the tuyeres may be located in different positions than those shown and the composition of the gas supplied thereto may be controlled from a single valve rather than from individual valves if desired. Finally, many of the features of this invention may be employed with a furnace of circular, oval, or other cross sectional shape as well as in a furnace of a rectangular cross section and the discharge funnels r hoppers 36, 37 may be provided with discharge valves providing a gas seal if the bed of pellets maintained upon the horizontal members 99 by the chains 100 be insutficient for this purpose. These and other changes will readily be suggested to those skilled in the art after having had the advantages of this disclosure and consequently it is to be understood that the construction shown and described is simply illustrative of the present preferred embodiment of the invention and that the latter is not to be considered as limited to the exact details shown and described.

Having thus described our invention, we claim:

1. In a shaft furnace of the character described, a plurality of spaced gate members extending substantially parallel transversely of said furnace adjacent the bottom thereof providing openings therebetween for passage of material in said furnace, a plurality of horizontally extending members supported in vertically spaced relationship below the spaces between said gate members to receive thereon material moving downwardly between said gate members, flexible means suspended from said gate members and adapted to engage the material on the secondnamed members to assist in defining the angle of repose of the material resting thereon, and means for imparting limited transverse reciprocating movement to certain of said second-named members to displace material resting thereon.

2. The combination as defined in claim 1 wherein the said gate members are movably supported on the sidewalls of the furnace, and means externally of said furnace cooperating with each of said gate members to effect adjustment thereof and to retain the gate members in an adjusted position whereby the spacing between said gate members may be varied to thereby control the rate of movement of material through said furnace.

3. The combination as defined in claim 1 wherein the said gate members are arcuate and the said flexible means are chains secured in spaced relationship along the length of each gate member and hanging below the lower edge thereof.

4. The combination as defined in claim 1 wherein the said members spaced below the gate members include stationary horizontally disposed plates and movable members, the said movable members including upwardly extending portions movable adjacent the upper surfaces of said plates to displace material therefrom, and the said means, for imparting limited reciprocating movement inelude separately operable means connected to said movable members, whereby the rate of movement of materials through any part of the furnace may be regulated by selective energization of said operable means.

5. In a shaft furnace of the character described, a plurality of curved gate members extending transversely of the interior of the furnace in spaced substantially parallel relationship adjacent the lower portion of the furnace, means supporting said gate members for individual limited arcuate movement towards and away from each other to thereby vary the sizes of the openings therebetween available for the passage of material, separate means externally of said furnace cooperating with each of said gate members respectively to effect adjustment of said gate members and to retain the gate members in the adjusted position, a plurality of members horizontally spaced from each other and supported in vertically spaced relationship below the spaces between said gate members to receive thereon material moving downwardly between said gate members, and means for imparting limited transverse reciprocating movement to certain of said second-mentioned members to displace material resting thereon.

6. In a shaft furnace of the character described, a plurality of curved gate members extending transversely of the interior of the furnace in spaced substantially parallel relationship adjacent the lower portion of the furnace, means supporting said gate members for individual limited arcuate movement towards and away from each other to thereby vary the sizes of the openings therebetween available for the passage of material, separate means externally of said furnace cooperating with each of said gate members respectively to effect adjustment of said gate members and to retain the gate members in the adjusted position, a plurality of members horizontally spaced from each other and supported in vertically spaced relationship below the spaces between said gate members to receive thereon material moving downwardly between said gate members, flexible means suspended from said gate members and adapted to on gage the material on the second-mentioned members to assist in defining the angle of repose of material resting thereon, and means for imparting limited transverse reciprocating movement to certain of said second-mentioned members to displace material resting thereon.

7. In a shaft furnace of the character described, a plurality of spaced breaker rolls journalled for rocking movement in the furnace with their axes extending horizontally transversely of the furnace, the rolls being so spaced as to provide open passageway between adjacent rolls, spaced outwardly extending projections on each of said rolls, means for imparting rocking movement to said rolls to effect breakage of large clusters of material therebetween, a plurality of spaced gate members extending transversely of said furnace beneath said rolls and projecting into the path of material passing between said rolls, means to individually adjust the positions of said gate members, a plurality of horizontally extending members supported in vertically spaced relationship below the spaces between said gate members to receive thereon material moving downwardly between said gate members, flexible means suspended from said gate members and adapted to engage material on said horizontally extending members to assist in defining the angle of repose of material resting thereon, and means for imparting limited transverse reciprocating movement to certain of said last-mentioned members to displace material resting thereon.

8. The combination as .defined in claim 7 wherein the said flexible means include a plurality of spaced chains secured to the said gate members and hanging below the lower edges thereof.

9. The combination as defined in claim 7 wherein the means for imparting limited movement to certain of the horizontally extending members include a plurality of separate driving means corresponding in number to the number of spaces between said gate members and each connected to a separate one of said horizontally extending members.

10. A furnace comprising a shell, a heat-resistant lining in a portion of said shell forming an unobstructed shaft-like material treatment chamber, a plurality of spaced tuyeres communicating with said chamber to introduce a gas therein for effecting heating of the material passing through said chamber, means to regulate the fiow of gas, and means to regulate the flow of material through said chamber including a plurality of spaced breaker rolls extending transversely of said furnace adjacent the bottom of said treatment chamber, the said rolls being spaced sufliciently to permit free passage therebetween of non-clustered material while any large clusters of material formed in said chamber are retarded by said rolls, individual power means for selectively rocking said rolls to break said large clusters, gate members beneath the openings between said rolls and projecting into the path of material passing between said rolls, means to adjust the positions of said gate members, horizontally disposed members positioned beneath the spaces between said gate members, and means for imparting limited transverse reciprocating movement to certain of said last-mentioned members to displace material resting thereon.

11. A furnace as defined in claim and wherein the said gate members are each provided with flexible means suspended therefrom to assist in defining the angle of repose of material on the said horizontally disposed members.

12. A furnace as defined in claim 10 wherein the individual power means for rocking said rolls comprise separate air pressure operated motors.

13. In a shaft furnace of the character described having a heating zone for heating pellets, a plurality of spaced breaker rolls below the heating zone and extending horizontally transversely of the furnace with their axes parallel, said rolls having spaced outwardly extending projections, means journalling said rolls in said furnace for individual rocking movement and supporting said rolls in spaced relation such that each of said rolls is spaced from the adjacent rolls a distance suflicient to permit the passage of individual pellets but sufficiently close to one another that the passage of large clusters of pellets is blocked, individual power actuated means operatively connected to each of said rolls to effect individual rocking movement thereof, the said power actuated means each including a motion producing member and a compressible medium acting thereon, and means to control the operation of said power operated means and thereby control rocking of said rolls.

14. The combination as defined in claim 13 and fur ther comprising means to circulate a cooling fluid through said rolls.

15. In a shaft furnace of the character described having a heating zone for heating pellets, a plurality of spaced breaker rolls below the heating zone and extending horizontally transversely of the furnace in the path of said pellets with theiraxes parallel, said rolls having spaced outwardly extending projections thereon, means journalling said rolls in said furnace for individual rocking movement and supporting said rolls in spaced relation such that each of said rolls is spaced from the adjacent rolls a distance sutficient to permit the passage of individual pellets but sufiiciently close to one another that the passage of large clusters of pellets is blocked, individual 14 a heating zone for heating pellets, a plurality of spaced breaker rolls extending horizontally transversely of the furnace below the heating zone with their axes parallel, each of said rolls having means thereon for striking clustered material and including a hollow tube with closed ends, shaft means extending outwardly axially of the ends of each tube and exteriorly of the walls of said fill? nace, the said shaft means of each roll having passages therethrough communicating with the interior of the tube thereof, means to circulate a cooling fluid through said shaft means and tubes, bearing means rockably supporting said shaft means and supporting said rolls in spaced relation such that each of said rolls is spaced from the adjacent rolls a distance sufiicient to permit the passage of individual pellets but sufliciently close to one another that the passage of large clusters of pellets is blocked, a separate crank arm connected to the shaft means of each roll, and separate power operated means connected with each of said crank arms to effect individual movement of said rolls and thereby facilitate discharge of material there between.

17. The combination as defined in claim 16 and wherein said means on each of said rolls for striking clustered material comprises a plurality of spaced projections.

18. The combination as defined in claim 16 and wherein the said power operated means are fluid pressure motors and separate valves are provided toindividually control the operation of each of said motors.

19, A furnace for heating pellets comprising a shell, a heat resistant lining in a portion of said shell forming an unobstructed shaft-like pellet treating chamber, means to introduce a gas into said chamber for effecting heating of the material while passing through said chamber including a plurality of spaced tuyeres and means for regulating the flow of gas therethrough, and means adjacent the lower end of said treatment chamber controlling the rate of passage of pellets therethrough including spaced breaker rolls extending transversely of said furnace adjacent the bottom of said treating chamber, means supporting said rolls in spaced relation such that each of said rolls is spaced from the adjacent rolls a distance suflicient to permit the passage of individual pellets but sufliciently close to one another that the passage of large clusters of pellets is blocked, power means for selectively operating said rolls to break said large clusters, and means beneath said rolls regulating the passage of pellets between said rolls.

20. A furnace adapted to indurate agglomerates of finely divided metalliferous material comprising a vertical shaft-like agglomerate treating chamber adapted to be maintained substantially full of downwardly moving agglomerates which are indurated by heating during the said movement, a plurality of spaced breaker rolls and including means for striking clustered material adjacent the bottom of said treating chamber in locations such as to be surrounded by the agglomerates and each roll having radially extending projections on the upper portion only thereof for striking clustered agglomerates, means journally supporting said rolls in spaced relation such that each of said rolls is spaced from the adjacent rolls a distance sufiicient to permit the passage of individual agglomerates but sufiiciently close to one another that the passage of large clusters of agglomerates is blocked, and power means operatively connected to said rolls for selective arcuately rocking of the latter to thereby break any large clusters of agglomerates formed in the said chamber.

21. A furnace adapted to indurate agglomerates of finely divided metalliferous material comprising a shell, a heat resistant lining in a portion of said shell forming a. vertical shaft-like agglomerate treating chamber adapted to be maintained substantially full of downwardly moving agglomerates, means to introduce a gas into said chamber for effecting induration of the agglomerates by heating while the latter move downwardly through the said chamher, a plurality of spaced breaker rolls extending transversely of said furnace adjacent the bottom of said treating chamber in locations such that the rolls are surrounded by the agglomerates and each roll having radially extending projections on the upper portion only thereof for striking clustered agglomerates, means journa-lly supporting said rolls in spaced relation such that each of said rolls is spaced from the adjacent rolls a distance sufiieient to permit the passage of individual agglomerates but sufficiently close to one another that the passage of large clusters of agglomerates is blocked, and power means operatively connected to said rolls for selective rocking of the latter about the axes thereof to break any large clusters of agglomerates formed in the said chamber and thereby facilitate discharge of the indurated agglomerates.

22. A furnace adapted to indurate agglomerates of finely divided metalliferous material comprising a shell, a heat resistant lining in a portion of said shell forming a vertical shaft-like agglomerate treating chamber adapted to be maintained substantially full of downwardly moving agglomerates, means to introduce a gas into said chamber for effecting induration of the agglomerates by heating while the latter move downwardly through the said chamber, a plurality of spaced breaker rolls extending transversely of said furnace adjacent the bottom of said treating chamber and in locations such as to be surrounded by the agglomerates and each roll having radially extending projections on the upper portion only thereof for striking clustered agglomerates, means journally supporting said rolls in spaced relation such that each of said rolls is spaced from the adjacent rolls a distance sufiicient to permit the passage of individual agglomerates but sufficiently close to one another that the passage of large clusters of 16 agglomerates is blocked, power means operatively connected to said rolls for selective rocking of the latter about the axes thereof to thereby break any large clusters of agglomerates formed in the said chamber, and means beneath said breaker rolls for effecting discharge of the indurated agglomerates from the furnace.

References Cited in the file of this patent UNITED STATES PATENTS 122,550 Barrett Jan. 9, 1872 1,058,034 Christensen Apr. 28, 1913 1,164,761 Simmons Dec. 21, 1915 1,609,128 Richardson Nov. 30, 1926 1,861,081 Foresman May 31, 1932 1,893,301 Norgren Jan. 3, 1933 1,948,992 Mon'n Feb. 27, 1934 2,013,680 Bennett Sept. 10, 1935 2,088,252 West et a1. July 27, 1937 2,108,118 Greenawalt Feb. 15, 1938 2,148,946 Hubmann et a1. Feb. 28, 1939 2,202,090 Colbert May 28, 1940 2,296,965 West et a1 Sept. 29, 1942 2,300,860 Azbe Nov. 3, 1942 2,498,766 Pettigrew Feb. 28, 1950 2,620,946 Aver Dec. 9, 1952 FOREIGN PATENTS 148,819 Great Britain Apr. 28, 1921 OTHER REFERENCES Metal Mining Practice Bulletin No. 419 of the U. S. Dept. of the Interior. Pages 196-198, published 1939. 

